Personally I don't think the show would be worth watching without the sex and violence, but that might just be me. To actually answer your question though I think many of the sex scenes actually establish character and subtleties of plot, and the same might also be said of the violence.
According to Here be Geeks about 2-3 minutes have been cut from each hour in Singapore, and they express concerns that many of these scenes
will be integral to the plot:
Some gore or sex could probably be safely edited out of the shows, but I fear that certain scenes will be rendered useless due to censorship. Lots of ... Game of Thrones eps have violence and gore that and (sic) in some way or another is integral to the plot, and while off the top of my head I think most of the boobs from Game of Thrones can be edited out, there’s that one key scene in a whorehouse that I think really speaks volumes about quite a major character and his worldview.